How to avoid conflicts in git?

Question

git

There is a main repository with one file.
Several developers fork this repository and start making changes to their copies.
After that, they send their pull requests to the main repository.
But from the moment when one sends a pull request, someone else has already managed to make changes to this file in the main repository.
And because of this, conflict arises.
I don't want to do it manually every time.
Advise how to solve the problem?
(the file cannot be split into several)

Answer 1

It's not up to you to decide, the developer, before making a pull request, must make it in his branch

git fetch
git rebase origin/master

and then solve all conflicts and only then
The only way to minimize conflicts is to beat the file into pieces.
If a person works in a fork, then he must first pull the changes to his master from the main repository

Answer 2

If you were sent a pull request with a conflict - send it back, the developer must redo it.
If conflicts are constantly pouring in, this is a reason to reconsider the work, or the pull requests are very large, or the code is mixed into noodles so that each change affects many areas, or the tasks are such that developers make changes in the same place.
This needs to be found out and corrected.

Answer 3

Show the file. Although, in general, it is worth organizing the work somehow. For example, tell developers to work on one atomic unit at a time.
For example, only 1 function was changed.